The present invention generally concerns subsea valve apparatus. More particularly, the present invention concerns fail-safe hydraulically operated valves located on underwater pipelines or flow lines. In the operation of remote underwater valves a piston-operated valve stem reciprocates within a cylinder to open and close the (gate) valve element. In a single acting valve stem cylinder system, power fluid forces the piston in one direction (power stroke) and a spring returns the piston to its starting position (exhaust stroke). In a closed hydraulic power system in the failsafe mode the operating or reservoir fluid pressure may be greater than the internal valve pressure. In that event the force due to the hydrostatic head i.e. the difference between the operating pressure and the valve pressure multiplyed by the piston stem diameter may be greater than the spring load in the piston operator and the valve may remain in the open position. The addition of another opposing valve stem, which is capable of contacting but is not connected to the valve element, balances the unwanted force permitting the spring to close the valve when the ambient pressure is greater than the internal valve pressure. When the internal valve pressure is greater than the ambient pressure the other valve stem does not engage the valve element which permits the valve system to function as a standard fail-safe valve.